Still new at this so please be nice. I have the TF100 test kit and my water is absolutely beautiful. One issue I just ran into in the last week. I noticed this week that all of the sudden I was getting a white ring around the tiles and on the rock waterfall. I haven't run a full test in about two to three weeks, but I do test at least every other day for PH and Chlorine. My PH has been staying around 7.6 when testing it and not changing. I added 20 oz of muriatic acid according to the pool calculator to bring it down to the 7.2 level. I tested again after waiting about an hour and my reading was the same. I added more muriatic acid, waited and it finally brought the level down to around 7.4. I then added what the pool calculator said to bring it down to 7.2 and it accurately did so. So my question is why when testing did my PH read 7.6 but it took almost 40 oz of muriatic acid to bring down? Do I just try to maintain my PH at 7.2 to try and remove the white ring and stains on my rock waterfall? My pool is only around 10K gallons. I will post a full test result when I get a chance. Thanks for your input.

Please post a full set of test results.

FC
CC
pH
TA
CH
CYA
Borates


High TA in particular can require more MA to lower ph. Borates also can increase MA needed to lower ph.

You may have had super high TA, which combined with a waterfall, pretty much guarantees that the pH will jump up again. Fast.

Play with the Pool calculator a little. Set the now and goal pH to 7.6 and 7.2 then play with changing the TA. You'll see the amount of acid needed will change.

My cya dropped from 70 the last time I did the full test. I use 6% bleach to chlorinate now and was using 3 inch tabs so it went from a really low number like 30 to 70 quickly. The FC of 9 was after I put my daily dose in the pool today. Also I do not have a test for borates.

FC: 9
CC: .5
pH: 7.2
TA: 110
CH: 350
CYA: 55
Borates: ?

Thanks

BTW - I do have a waterfall and 5 laminar jets that we use constantly.

Yep that will raise ph. Good news is, the process of lowering it will, over time, also lower/continue to lower your TA. 70-90 are considered good starting point for TA on a non-swg pool. From there, you can experiment with going lower if you need to.

So do you think my testing was correct and PH was 7.6/7.7? Is that enough to start leaving the scale build up around the pool?

I used poolcalculator to calculate your CSI with 7.7 ph and got +.3 which should be okay. Any chance your ph is higher very often?

I am not experienced in scale...hopefully someone else will speak up.

I'd say that if your pH hit 7.8, or higher, and your water temperature were 88 F, or higher, then scale would be possible to likely.

With a TA of 110 and plenty of aeration, then it's likely that the pH has reached 7.8 or higher unless you have been watching it very carefully.

Well from testing I never saw the colors get above 7.8 and looked more like 7.5+/-. My water on the other hand has gotten easily over 97 everyday as we are having extremly hot weather here in SE Texas. I am going to try and keep the PH lower towards 7.2 and also lower TA as well. Will the build up come off over time? I can get the white line off with a pumice stone on the tile but the rock waterfall won't like that. Thanks

Scale does not typically come off on its own unless the water gets pretty aggressive. Getting the water aggressive enough to remove scale will usually cause problems with other elements of the pool.

You could try some muriatic acid on a test spot to see if it will remove the scale without causing damage to the underlying material. Use a toothbrush or other small brush to control the application of the acid.

Is this a concrete pool, and if yes, how old is the plaster?

OK. Still having some weird issues with PH. My TA is now down to 90 yet I am still adding double the amount of muriatic acid to lower my ph. I tested this afternoon and my ph was 7.4+ so I added 11 oz of acid to bring it down. I waited almost an hour and tested again. It did nothing as it was still reading 7.4. I added another 11 oz and tested withing 45 minutes and my ph was now at 7.2 What gives? I am not complaining as my water is absolutely beautiful and sparkles in the sun, but why am I adding double the amount of acid? My pool is approximately 10K gallons. BTW - the white scale line is much better now without even scrubbing.

Some acid is a lower concentration. Full strength is 31.45 %.

I have the 31.45%. I had the same thought and even bought two new bottles of it to just make sure. Could it be the high water temperatures? My pool is getting to 97+ every day. I wish we would have one week at 90 this summer so we can really enjoy our pool.

High water temperatures will cause carbon dioxide to off gas faster, so it could be related.

Today was the first day in months the temperature stayed below the 90's. When I tested the PH today it was at 7.4+, so I added acid as the pool calculator suggested, and it went straight to 7.2 after testing again in 1 hour. Also note that today instead of using the usual 84 oz of clorox I only required 6 oz to bring it back up to 9. I am still keeping FC high as it is supposed to go back to 107 this weekend. Usually it takes 21oz to bring the FC back up 1 ppm. Anyway my pool still looks awesome and sparkles in the sun. According to the weatherman the weather pattern is supposed to change the 1st week of Sept. I can only hope that it is for the better.